Knife sharpening mechanism for cutting machines



April 28, 1942 F. J. CLARK ETAI. l 2,281,023

` KNIFE SHARPENING MECHANISM FOR CUTTING MACHINES ff ffm, Qdmrffw.

April 2s, 1942. F, CLARK ETAL 2,281,023

KNIFE SHARPENING' MECHANISM FOR CUTTING- MACHINES Filed Jan. 19, 1940 2 Sheets-Sheet 2 'lll/[11010. l0 l /A/ VEN refs Patented pr. 28, 1942 KNIFE SHARIENING MECHANISM FOR I CUTTING g MACHINES Frederick J. Clarkand Frederick GfClarkgBuf 'to Eastman Machine Comfalo, N. Y., assignors pany, Buffalo, N. Y.

Application January 19, 1940seria1No-c14s6 s ciaims. (c1. 51;-246) `This invention relates to improvements` in knife-sharpening mechanisms for cutting ma-` chines of `the type, commonly used for cuttingv cloth and other sheetmaterials, having an uprightvertically reciprocating knife with a substantially vertical cutting edge which can be` caused to follow a desired pattern or line of cut in a lay of cloth or other material by appropriately moving and guiding the machine about upon` the supporting table for the material.

One object of the invention is to improve in certain respects, hereinafter pointed out, sharpening mechanisms of the general character disclosed in U. S. Letters Patent No; 2,183,786, granted December 19, 1939, to Frederick J. Clark (one of the applicants hereof), assigner to Eastman Machine Company.

Further objects of the invention are to provide efficient and desirable drive means of novel construction for the knife grinding means or ele ments of sharpening mechanisms for such ma` chines; also to` provide novel and improved means for guiding and holding theiiexible band grind` ing means or belts of such mechanisms in sharpeningcontact with the machine knife.

These and other objects and advantages of the invention will appear more fully from the following specification of the preferred embodiment of the invention, disclosed in the accompanying' drawings, and the novel features of the invention will be set forth in the appended claims.`

In the accompanying I drawings: Fig. 1 is a front sectional elevation on line I-I,

Fig. 2, of a cutting machineequipped with knifef' sharpening mechanism embodying the invention.`

Fig. 2 is a side elevation thereof, partly in` sec; tion, on line 2-2, Fig. 1.

Fig. 3 is a fragmentary Yfront elevation`- of theY meansforholding the sharpening beltaway from"` theknifel when it is moved below the lower end of `the knife. I

Fig. 4 is a sectional plan view of the grinding I means.` I

Fig.: 5 is a sectional elevation thereof andof the grinder carriage on line 5-5, Fig. 4r

Fig. 6 is a section on `line `I6 of Fig. 4,

Fig. 7 is an enlarged, more or less diagram--V matic, sectional plan showing the relation of the grinding belts and holding elements to the knife.

Fig. 8 is a sectional plan view of holding and guiding means of modified form for the sharpening belts.

Fig. 9 is a side elevation thereof.

Fig. 10 is a sectional view thereof on line IU-I B, Fig.,8.

Fig. 11 is a sectional plan thereof on II,Fig. 10.

The'cutting machine, aside from the knifesharpening mechanism and associated parts, may be of the construction illustrated in the drawings or of other known or suitable construction. As` herein disclosed-it comprises,'as usual, a base I5 adapted to rest and be moved about upon the table ork supporti-surface on which material to be cut lies, an upright, rigid standard` I6 rising or housing Il of an V'electric motor I8, Vwhich re#- from the base and supportinga stationary `frame ciprocates the vertical knife I9 ina guide slotA inthe front of thestandard through drive'con-` nections comprising la slide tofwhich the knife is attached at its upper end and 'whichis connected by a pitman 2l to a crank wheel 22 on the front enel` of a horizontal rotary shaft of the* motor.

23 indicates the usual presser foot fixed to therY `lower end of a rod24 which extends vertically in front of fthe knife I9, forming a guard therefor.

This rodis adjustable vertically in a` suitable guide 25 on the frame and is releasably fastened l by means `(not shown), to support thepresser foot at ldifferent elevations suited to different laysH of material tobe cut.' The rear endof the presser foot shown is bifurcated and straddleslthe front edge portion of the standard to assist in `prevent-- ing lateral deflection of the guard rod.

In the preferred embodiment, of my invention? illustrated in the drawings, the knife is sharp-- ened by flexible band grinding means, preferably comprising flexible belts or strips 3l) and 3|,"hav-` `ing grinding surfaces of carborundum or otherk suitable abrasive material, disposed `'and operated in such a way that they travel in sharpening contact with opposite sides of the edge portionof the knife. Said grinding means,`like` those shown in the aforesaid patent, are power driven, for eX- ample by the knife-operating motor I8, so that the band stretches or portions of the belts which contact with the knife travel at high speed past the latter, and they are mounted on a grinder carriage 32 arranged to be moved up `and""'down' along the knife to enable the sharpening of the knife edge throughout its full length. Said band" grinding means, together with theY drivemecha-` `nism therefor, and other operative parts of the `sharpening mechanism maybe mountedpas disclosed in said patentyon a cover-piece or housing I 33, Whichis stationarilyY but removably secured in place at the frontlof `the-macllirn andservesto cover the erankwheel 22 and other parts of the I knife-operating mechanism'.

The mechanism for driving the knife-grinding means is preferably constructed as follows:

35 and 36 represent two vertical shafts arranged in front of the knife at opposite sides of the plane thereof, to rotate and slide axially in suitable bearings 31 and 31a in the housing 33. These shafts extend downwardly out of the lower end of the housing with their lower portions journalled and held from axial movement in suitable bearings in the grinder carriage 32 so that the shafts will move up and down with the carriage. The shafts may extend through and above the upper end of the housing, thereby enabling the shafts to be made long enough to permit sufficient vertical travel of the.v grinder carriage for sharpening a knife of the maximum length without requiring the housing 33 or the machine to be of objectionable height. Shafts 35 and 36 are rotated in opposite directions by gearing comprising a train of intermeshing pinions 39, 46 and 4| which'are held from endwise movement in a chamber 42 in the lower portion of the housing 33. and shafts 35 and 36 are connected to rotate with pinions 39 and 40 but slide axially therethrough,l as by keys projecting from the pini-ons into longitudinal keyways 43 in the shafts.

YThe toothed pinions 39-4I are shown disposed with their axes parallel, and the pinion 4| is splined on the lower end of a third shaft 44. Preferably, this shaft is journalled in suitable bearings7 in the housing 33 at one side of shafts 35 and 36 and is geared at its upper end, as by two-intermeshing spiral toothed pinions 45, 46 to a horizontal shaft 41 on which is fixed a wheel 48 arranged to be driven by the crank wheel 22. As shown, the shaft 41 and pinions 45, 45 are suitably mounted in a gear casing 49 which is arranged above the housing 33 to move vertically toward and from the same, as on guide posts 56, one of which is shown in Fig. 2, fixed to and rising from the housing 33 through guide holes in the gear casing. The gear casing is pressed downwardly to hold the wheel 43 in driving leni gagement with crank wheel 22, as by springs 5| surrounding posts 50 between the gear casing and` nutsy or heads at the upper ends of the guide posts. The wheel 48 may be driven by frictional contact with the crank wheel, for which purpose the latter may be provided with a peripheral band or tire 52 of rubber or other material adapted t give the necessary frictional contact between the wheels for properly driving the wheel 48' and the grinding means geared thereto. Pulleys 53 and 54 fixed directly on the lower ends of shafts 35 and 36, constitute supporting and drive pulleys for the knife-sharpeningbelts 3IA and 3|. Each of the belts 30 and 3|, as in the aforesaid patent, passes around one of the drive pulleys 53, 54 andv an idler pulley 55, the idler pulleys being journalled on spring-pressed mountings 56 movable toward and from the drive pulleys on rearwardly projecting legs 51 of the grinder carriage which straddle the knife standard. These movable idler pulleys maintain the belts under'suitable tension and allow ready removal and renewal of the belts.

When sharpening the knife, the grinder carriage 32 will be moved down and up from an upper position spaced somewhat below, the lower end`of the housing 33 to cause the belts 30, 3| to grind all portions of the knife edge, and the springs will hold the wheel 48 in driving engagement with the crank wheel 22,'and hold the lower'end of shaft 44 projecting below the bottom of housing 33. The drive gearing described 1 and 2, by suitable means, such as the latch disclosed in said patent.

By constructing the drive gearing for the grinding means as described, the pulleys for the grinding belts are fixed directly to the sliding shafts 35, 36, gearing on the grinder carriage is eliminated, and only two gear trains comprising five pinions in all, are required. Furthermore, no tubular or telescoping shafts are necessary and the gearing is composed wholly of rigid shafts and, The mechanism is also compact, does not obscure the View of the operator in thee use of the machine for cutting and does not lessen the desired, attractive, trim appearancev gear wheels.

of the machine,

In said patent, the two sharpening belts, which. are disposed one above the other, or in staggeredv relation, are yieldingly pressed into grinding con-- tact with opposite sides of the edge portion Vof,I

These fin-- gers, as shown in the patent, are pivoted on the carriage legs and have fixed portions which bear against the back faces of the belts, and against'I which the belts travel, to hold the belts against.

the knife by spring pressed fingers.

the knife.

A cutting machine of the type for which the: sharpening mechanism is designed is used at dif-- ferent times for cutting cloths or materials which. A very' keen edge has to be kept on the knife to efficient ly cut some kinds of materials, while some other materials are very hard or tough, and if too thin an edge, or a feather edge is formed on the knife,. such materials will quickly damage or dull the edge, thus destroying or greatly impeding its. cutting action. But the operators of such ina-- chines are not ordinarily the type of skilled rne-V chanics who can be relied upon to sharpen the,A knife to provide one or another kind of edge asI may be best suited to meet the requirements of i properly cutting such different kinds of materials,. and it is important thatI the sharpening mecha-.- nism b'e designed so as not to require the skill.. of a sharpening expert during the use of the ma-y Due to the high speeds at which the: grinding belts travel, the frictional contact, of.' the belts with the parts of the devices that holdiand guide the belts in grinding contact with the:

differ greatly in physical characteristics.

chine.

knife will wear or cut the surfaces ofsuch parts, so that if such parts are fixed, or incapable of adjustment or renewal, they will become so worn in a comparatively short time as to cause change in the positions of the belts relatively to the knife edge and thus improperly grind the edge or change the character of the edge ground by the belts.

In order to avoid this objection and provide guide and holding devices for the belts having the portions or surfaces which engage the belts constructed so that they can move to repeatedly present new engaging surfaces for the belts and thereby prevent the engaging surfaces from being worn or ground to an objectionable extent;

ages-ncaa: or soth'at they can 'bechanged` orfadjustedto present newi surfaces for engagement with the beltslbefore the engagingI portions become ob-` Asshown in Figs. l-'7,1 these devices comprise arms Slsuitably pivotedfatfl onfthe underside of the carriage legs T and extending forwardly from their pivots at opposite sides of the knife. Near the edge portionof the knife a guide roller 62i`sjournalled, as by a screw stud 64, to rotate freelylon each pressure arm 6I). These rollers 62', which may be metal rollers, are arranged so as to bear against the back faces of the inner runs or stretches of the belts at points adjacent to, and preferably slightly in front of, `the edge of f the knife,` and ai'eyieldingly pressed against thebelts, as by springs 65 coiled about the arm pivots 6l, `with the opposite ends of each spring engaging the related pressure arm and the carriage leg. The springs act topress the rollers and thefbeltstoward the knife. Preferably, the guide` rollers are located, as indicated in Fig, 7 of the drawings, so that each belt will be yieldingly pressed against the edge portion of the knife `slightly in rear ofthe point of tangential Contact of the belt with the roller 62. By this disposition of the'` parts, the roller does not form afstr-ictly rigid backing for that portion of the belt which-is in'grinding contact with the knife, but there is more or `less` tendency for the belt to leave the-periphery of the roller where the belt contact-s with the knife.` Since the belt is stretched or heldunder tension between its drivl ing and `idler pulleys, andthe guide roller deflects the portion of the belt which it engages toward theknife, there isscme drag of that portion of the belt whichis held in grinding contact with theknife'and, as a resultran improved sharpening` ofthe knife is obtained.

Because of the described relationship of the grinding belt, guide rollers and knife, the grindg `ing belts will give the knife the required keen edge having relatively `long and substantially flat rather thanhollcw ground bevel faces, but will be prevented from forming an edge which is too thin to stand up when cutting some kinds of materialswith which the machine has to be used.1 On the other hand, the belts will not grind a short hollow ground edge such as'` would be produced by the use of circular abrasive wheels. Since the guide rollers are rotated by contact with thebelts, they will wear very much longer than xed or stationary guide surfaces contacting with the belts,` and will operate a long time without being worn to-an `extent sufficient to interfere withithe proper sharpening action of the belts.

Figs.-8ll illustrate belt guide and holding devices lof a modiiied construction in which, instead p of the freely rotating rollers 62, guide blocks 'l0 are mounted `on the pressure arms B in such a manner that the blocks can be adjusted to present different portions thereof to engage the belts so that before one portion becomes Worn to an objectionable extent, the position of the block can be readily adjusted to present a new engaging surface to the beltl.` As shown in these figures, each block 'lf3 is rotatably mounted on a pivot stud 'fl fixed on the arm B0 and is provided with cross grooves 'l2 in its upper end, in either of which grooves a pin or lug 'I3 fixed on the underside of the arm 60 is adapted to engage for preventing or limiting rotation of the block `on -the pivot;` The block, as shown, is removably securedionxthe :pivot stud by-a screw I4 which is!- screwed `intothe studfandhas an enlarged head underlyingrthe'lower end` of the block. A coil spring l5ssurrounding` the stud in a central cavity in` the` block reacts between the screw head and thebottom.` of the block cavity to press the block upwardlyA against thearm 6B and thus prevent the disengagement of the lug 'I3 on the arm from the` groove `in the upper-,end ofthe block. By looseningthe screw and pulling the block outwardly, sufficiently to disengage the lug` 'I3 from the block groove, theA block can be turned to engage the lug in another groove and thus hold the block inadifferentposition to present a different surface portionythereof for` bearingagainst the belt. The grooves in the block are somewhat wider than `the lug, so that notwithstanding theprojection of thelug 'I3 into-any oneof the grooves, a limited angular or rotational adjustment of the block is permitted. This allows the angle between theblock face, which engages the belt, and the knife edge to be altered sufciently to shorten .l or lengthen the bevel ground by the belt on the knife, edge, and thus enables the character of the edge to be changed to best suit the material to be. cut. The pressure of the spring 'i5 will retain the block atthe angle to which it is thus adjusted. ItA will be` understood that `this angular adjustment is independent of the rotation of the block` to different positions to present different peripheral faces of the block for` engagementwith the belt. The block is preferably provided with a projecting handle` 'l5 for conveniently adjusting it without danger tothe operator of cutting his This handle preferably consists of a` Z-shaped bar provided with an annular end porfingers.

groove in the upper end of the block and engaged inanother groove so that the handle may occupy the same position` relatively to the arm, in the different adjustments of the block, and the handle will not be placed so as to strike or interfere with the grinding belt by the adjust` ment of the block.

As best shown in Figs. Sand 4, the pressure arm Gil for the lower sharpening belt has a forwardly projecting extension 30 with an inwardly directed end portion Ladapted to engage a cam 8| on the lower portion of the guard rod 24 when the grinder carrier carriage is moved down- Wardly far enough to carry the lower belt below damage by contact of the guide elements with the knife.

We claimf 1. In a knife sharpening mechanism comprising .a flexible abrasive band which .travels past the knife in a direction toward a point in advance of the knife edge, and means for guiding and yieldingly holding said band in grinding contact with the edge portion of the knife including a guide element which the band travels past` and engages only at a peripheral portion thereof adjacent to the extreme edge of the knife, and means for pressing the guide element yieldingly towards the knife, said element being movable toward and from the knife for its yielding action and in addition being adjustable in a direction at an angle'to its direction of yielding motion for changing the angular relation of its said bandengaging portion and the band to the plane of the knife.

2. A knife sharpening mechanism comprising a flexible abrasive band which travels past the knife in a direction toward a point in advance of the knife edge, and means for guiding and yieldingly holding said band in grinding contact with the edge portion of the knife including a guide element which said band passes and engages at a peripheral portion thereof adjacent the edge of the knife, said element having bandengaging surfaces disposed angularly to each other, and said element in addition to its yielding action being rotatably adjustable to present one or another of said surfaces for engagement with the band and also to change the angular relation between the band and the edge portion of the knife.

3. A knife sharpening mechanism comprising a flexible abrasive band which travels past the knife in a direction toward a point in advance of the knife edge, and means for guiding and yieldingly holding said band in grinding contact with the edge portion of the knife including a spring-pressed support, a guide element rotatably mounted on said support and having angularly disposed band-engaging surfaces each adapted for engaging the band at a point adjacent to the cutting edge, a stop on said support, and parts on said element each arranged to cooperate with said stop by rotation of said element to place a different one of said surfaces in band engaging position.

4. A knife sharpening mechanism comprising a flexible abrasive band which travels past the knife in a direction toward a point in advance of the knife edge, Iand means for guiding and yieldingly holding said band in grinding contact with the edge portion of the knife including a springpressed support, a guide element rotatably mounted on said support and having angularly disposed band-engaging surfaces each adapted for engaging the band at a point adjacent to the cutting edge, a stop on said support, grooves in said element disposed at an angle to each other and each of which said stop is adapted to enter by rotary adjustment of said element for placing a different one of said surfaces in band engaging position, said stop having play in said grooves to allow adjustment of said element when any of said surfaces is in operative position to change the angular relation between the band and the edge portion of the knife.

5. A knife sharpening mechanism comprising a flexible abrasive band which travels past the knife in a direction toward a point in advance of the knife edge, and means for guiding and yieldingly holding said band in grinding contact with the edge portion of the knife, including a spring-pressed support, a guide element rotatably mounted on said support and having angularly disposed band-engaging surfaces each adapted for engaging the band at a point adjacent to the cutting edge, a stop on said support, parts on said element each arranged to cooperate with said `stop by rotation of said element to place a different one of said surfaces in band engaging position, and a handle projecting from said element for turning it, said handle being adjustable relatively to the element so as to project in the same direction in different adjustments of the element.

6. In a knife sharpening mechanism for cutting machines having a knife which reciprocates substantially in the lengthwise direction of its cutting edge and has a free extremity, comprising a flexible abrasive band which travels past the knife in a direction toward a point in advance of the knife edge, means for guiding and yieldingly holding said band in grinding contact with the edge portion ofthe knife including a guide element which said band passes and engages, and a spring for pressing said element against the knife, said sharpening mechanism being movable lengthwise along said cutting edge, a finger projecting from said guide means, and a relatively stationary device arranged in position to be engaged by said finger when said sharpening mech- Ianism is moved toward the free extremity of the knife and constructed to shift said finger when engaged thereby in a direction to remove the band from contact With the knife when the band has been moved past the free extremity of the knife.

7. A knife sharpening mechanism for cutting machines having a knife which reciprocates substantially in the lengthwise direction of its cutting edge, and a guide for the knife, said mechanism comprising a exble abrasive band which travels past the knife edge, and means for guiding and yieldingly holding said band in grinding Contact with the edge portion of the knife including a guide device which said band passes and which eng-ages and presses the band toward the knife, and a part on said device arranged to engage the knife guide to limit movement of said device toward the knife in case of breakage of said band.

8. In a knife sharpening mechanism comprising a flexible abrasive band which travels past the knife in a direction toward a point in advance of the knife edge, and means for guiding and yieldingly holding said band in grinding contact with the edge portion of the knife, including a guide element which said band travels past and engages 'at a peripheral portion thereof adjacent the edge of the knife, said element having peripheral band-engaging surfaces disposed angularly to each other, and said element in addition to its yielding action being rotatably adjustable to present one or another of said angularly disposed peripheral surfaces for engagement with the band.

FREDERICK J. CLARK. FREDERICK G. CLARK. 

